For example, Japanese Patent No. 4220453 discloses an interesting coil component. Japanese Patent No. 4220453 discloses several examples of a coil component called multilayer inductor and a cross-sectional configuration of a typical example among them is illustrated in FIG. 10.
A coil component 1 includes a component main body 2 with reference to FIG. 10. The component main body 2 has a substantially rectangular parallelepiped shape having first and second main surfaces 3 and 4 opposing each other, first and second side surfaces (which extend in parallel with a paper plane of FIG. 10, not illustrated) opposing each other, and first and second end surfaces 5 and 6 opposing each other. The first and second side surfaces and the first and second end surfaces 5 and 6 connect the first and second main surfaces 3 and 4.
First and second external terminal electrodes 7 and 8 are formed on regions of the second main surface 4 of the component main body 2 at the first end surface 5 side and the second end surface 6 side, respectively. These first and second external terminal electrodes 7 and 8 are formed by applying conductive pastes and baking them, and extend from the second main surface 4 to a part of the first end surface 5 and a part of the second end surface 6, respectively, in substantially L-shaped forms. In other words, the first and second external terminal electrodes 7 and 8 are not formed on the first main surface 3 and on regions of the first and second end surfaces 5 and 6 at the first main surface 3 side.
The component main body 2 has a laminate structure in which a plurality of insulating layers 9 are laminated in a direction orthogonal to the above-described side surfaces. A coil conductor 10 is arranged in the component main body 2. The coil conductor 10 is configured by a plurality of circulating conductor layers 11 each of which extends so as to form a part of a substantially ring-like trajectory along an interface between the insulating layers 9 and a plurality of via hole conductors (not illustrated) penetrating through the insulating layers 9 in a thickness direction thereof. The coil conductor extends in a substantially helical form by alternately connecting the circulating conductor layers 11 and the via hole conductors. In FIG. 10, the coil conductor 10 extending in the substantially helical form is illustrated in a state of being seen through in a direction of a center axis line thereof.
One end and the other end of the coil conductor 10 are connected to the first and second external terminal electrodes 7 and 8, respectively, while first and second extended conductor layers 13 and 14 formed along interfaces between the insulating layers 9 are interposed therebetween.
When the coil component 1 is mounted on a circuit substrate (not illustrated), the second main surface 4 serves as a mounting surface facing the circuit substrate. Accordingly, a direction of magnetic flux that is applied by the coil conductor 10 is parallel with the mounting surface.